Rosuvastatin calcium is known by its chemical name as 7-[4-(4-flurophenyl)-6-isopropyl-2-(N-methyl-N-methyl sulfonyl amino)-pyrimidin-5-yl]-(3R,5S)-dihydroxy-hept-6-enoic acid Calcium salt of formula I as given below.
which is known to inhibit the HMG-CoA reductase, and subsequently suppress the bio synthesis of cholesterol. Rosuvastatin calcium is useful in the treatment of hyper cholesterolemia, hyperlipoproteinemia, and atherosclerosis. Rosuvastatin calcium may form hydrates with a varying content of water.
EP-A1-0521471 describes in the preparation of Rosuvastatin calcium in powder form. Rosuvastatin sodium is dissolved in water at room temperature and an aqueous calcium chloride solution is added dropwise. The collected precipitate is an amorphous powder. U.S. Pat. No. 6,777,552 discloses the preparation of Rosuvastatin calcium through hydrolysis of methyl 7-[4-(4-fluorophenyl)-6-isopropyl-2-[methyl(methylsulfonyl)amino] pyrimidin-5-yl]-(3R,5S)-3,5-dihydroxy-(E)-6-heptanoate with calcium hydroxide in a water/ethanol solution.
WO 00/42024 discloses a crystalline form, hereafter referred to as Form A of -[4-(4-flurophenyl)-6-isopropyl-2-(N-methyl-N-methyl sulfonyl amino)-pyrimidin-5-yl]-(3R,5S)-dihydroxy-hept-6-enoic acid calcium salt and hydrates thereof, which are prepared by dissolving amorphous Rosuvastatin calcium form in a mixture of water and an organic solvent such as acetone or acetonitrile under heating and then cooling the solution to precipitate crystalline Form A.
WO 2005/023779 discloses another crystalline form, hereafter referred to as Form B of 7-[4-(4-flurophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)-pyrimidin-5-yl]-(3R,5S)-dihydroxy-hept-6-enoic acid Calcium salt which is prepared by slurrying of Amorphous Rosuvastatin calcium in water at 40° C. to get crystalline Form B. US20080194604 describes another new process for the preparation.
US 20080194604 discloses another crystalline form, hereafter referred to as Form C of 7-[4-(4-flurophenyl)-6-isopropyl-2-(N-methyl-N-methylsulfonylamino)-pyrimidin-5-yl]-(3R,5S)-dihydroxy-hept-6-enoic acid calcium salt.
Crystalline forms often show desired different physical and/or biological characteristics which may assist in the manufacturing or formulation of the active compound, to the purity levels and uniformity required for regulatory approval. Crystalline forms of such active compounds may also possess improved pharmacological characteristics, for example, improved bioavailability, and therefore, novel crystalline forms offer enhanced possibilities to modulate and design improved drug products. As crystalline forms A, B, C etc of Rosuvastatin calcium involves very tedious processes which are difficult to use at plant level since the material becomes sticky when stirred initially, results dull colour of material and the product does not crystallize after adding anti-solvent if dissolved in the solvent used. Some of these forms have very high water content which can affect the stability of the product, therefore there was a need for other crystalline forms of 7-[4-(4-flurophenyl)-6-isopropyl-2-(N-methyl-N-methyl sulfonylamino)-pyrimidin-5-yl]-(3R,5S)-dihydroxy-hept-6-enoic acid calcium salt or Rosuvastatin Calcium of improved colour having low water content & simplified process which is easy to handle at plant level, to have a sufficient diversity on crystalline materials to optimize manufacture, formulation and biological efficiency.